3-D printing, which works by building parts in layers, is a process used for the building up of 3-D models. 3-D printing is relatively speedy and flexible allowing for the production of prototype parts and tooling directly from a CAD model, for example.
Using 3-D printing enables the manufacturer to obtain a full 3-D model of any proposed product before tooling thereby possibly substantially reducing the cost of tooling and leading to a better synchronization between design and manufacturing. A lower product cost and improved product quality can also be obtained.
Various systems have been developed for computerized 3-D printing. Known systems include a system developed by 3-D Systems Inc. of California, USA which operates on the basis of stereo-lithography wherein a focused ultra-violet laser is scanned over the top of a bath of photopolymerizable liquid polymer plastic material. The surface of the bath is polymerized on contact with the UV laser creating a solid plastic layer at or just below the surface.
U.S. Pat. No. 5,387,380 to Cima et al. describes a technique for providing layered parts by depositing a layer of powder material and then depositing a binder material in selected regions to produce a layer of bonded powder material at the selected regions. These steps are repeated for successive layers to form a desired component. Following heat treatment, unbound powder is removed, leaving the fabricated part.
U.S. Pat. No. 5,287,435 to Cohen et al. describes apparatus for producing 3-D models which includes apparatus for depositing layer-by-layer, a photopolymer material in a selectable configuration and apparatus for curing each layer prior to deposition of the succeeding layer.
A disadvantage of these systems is the difficulty of printing 3-D models having a complex structure such as a tea cup, for example (shown in FIG. 2).
In U.S. patent application Ser. No. 09/259,323, now U.S. Pat. No. 6,259,962, to the Assignees of the present application, and incorporated herein by reference, there is described an apparatus and a method for 3-D model printing. U.S. patent application Ser. No. 09/259,323, now U.S. Pat. No. 6,259,962, describes apparatus including a printing head having a plurality of nozzles, a dispenser connected to the printing head for selectively dispensing interface material in layers and curing means for optionally curing each of the layers deposited. The depth of each deposited layer is controllable, by selectively adjusting the output from each of the plurality of nozzles.